The E-Fuse Kicks the Classic Blade-Style Fuse to the Curb
From the March/April 2025 issue of Car and Driver.
Like Odor-Eaters in workout shoes, a fuse doesn't call attention to itself until it stops working. These circuit breakers have two states: letting power flow or abruptly interrupting that flow due to a spike in current. To fix your car in the event of the latter, you must first find the fuse itself and then attempt to remove the thing with the often uncooperative small tweezers an automaker provides for such extractions. But it doesn't have to be this way.
Enter the e-fuse. All fuses deal in electricity, but here, the "e" prefix refers to the device's connected nature. E-fuses, which are placed into a computer chip, function like a mash-up of a fuse and a relay (basically an electrically powered switch) but with way more brains.
Because e-fuses react more quickly to over-current events, the wiring on the output side isn't subject to large current spikes and thus can be less robust, saving weight, space, and money. Since the computers are always watching, voltage and current monitoring takes place in real time, allowing a vehicle to log any incidents for later troubleshooting. An e-fuse's controller can diagnose issues on the fly and remedy them in the background with a self-healing reset.
At their inception, the Rivian R1T and R1S relied on ordinary fuses. However, as part of an update for 2025, Rivian overhauled the models' electrical architecture, jettisoning blade-style fuses for more than 200 e-fuses that now control various vehicle subsystems. (A few old-school fuses remain because of packaging necessities.) Rivian isn't the only automaker embracing e-fuses; Tesla, for instance, also uses them.
E-fuses have allowed Rivian to reduce the number of task-specific electronic control units by switching from a domain to a zonal architecture. Instead of grouping functions together by related purpose (window regulators, for example) and wiring them to a central controller, zonal architecture decentralizes things by placing the multi-function controllers into specific vehicle "zones."
Onsemi, a manufacturer of this tech, offers a four-channel e-fuse that can monitor up to a quartet of power streams at once or combine inputs and outputs to offer more current protection. Onsemi's e-fuse can also oversee 12-, 24-, 36-, and 48-volt sources, a valuable versatility when not all subsystems use the same voltage.
As expected of something with an integrated circuit, an e-fuse carries a higher up-front cost than its metal-blade counterpart. But in addition to better diagnostic coverage, e-fuses provide more precise power control, helping prevent the phantom drain from systems functioning in a low-power "sleep" mode. E-fuses also allow for changes—either during development or down the line as part of an over-the-air update—to be a true zero-touch proposition.
And best of all, they never need to be replaced. Good riddance to bad tweezers.
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Specifications Specifications Year Make Model Trim Vehicle Type: front-engine, rear/4-wheel-drive, 5-passenger, 5-door wagon PRICE Base: $18,000 (est) //Base price of vehicle as described in specs hed// Options: Option 1, $XXXX; Option 2, $XXXX ENGINE SOHC 12-valve V-6, iron block and aluminum heads, port fuel injection Displacement: 181 in3, 2958 cm3 Power: 150 hp @ 4800 rpm Torque: 180 lb-ft @ 3400 rpm TRANSMISSION 5-speed manual CHASSIS Suspension, F/R: control arms/live axle Brakes, F/R: 11.3-in vented disc/11.6-in drum Tires: Bridgestone Desert Dueler M+S DIMENSIONS Wheelbase: 103.3 in Length: 196.5 in Width: 68.1 in Height: 67.3 in Curb Weight: 4050 lb EPA FUEL ECONOMY (PROJECTED) City/Highway: 16/18 mpg C/D TESTING EXPLAINED
